I like to see Goku as a little boy get beaten up without his shirt. Baby did it all best, since Goku could barely fight back. Once he lost his shirt, it was it for him, and Baby punching him looks like it hurts.
When baby beats him up, the best part is when he pummels Goku's little body into the mountain and dirt. It looked really painful, including the two times he was hit in his tummy. I wish Baby abused the little Goku more, since it'd be easy to. Goku was shirtless, a weak beaten child, and not trying to get away. He didn't try to stop any hits either, specially tummy punches.
I think beating Goku up when he went shirtless was Baby's favorite thing too. He got to torture a little saiyan boy, attacking his shirtless body more and more until he couldn't stand anymore. I just wish he went extra long on the beating part, since Goku deserved to be beaten up.
It was good though that Goku laughed at Baby. It made him mad, so he'd punch Goku's body hard. It's the best shirtless fight.